Now to work down the top. I want the top to look thick so instead
of just extruding down once and stretching the vertices out. Lets
do this in a couple steps.
With the bottom row of vertices still selected.
Hit E to Extrude. Edges.
Hit Z to stay on the z plane.
Hit -minus on the keypad.
Hit .2 Enter. -0.2 on the global Z.
See image